Typically, a bogie of a railcar is constituted by wheels, axles, and a bogie frame, and the bogie frame includes a cross beam extending in a railcar width direction and a pair of side sills respectively joined to both ends of the cross beam by welding or the like and extending in a front-rear direction. Axle boxes respectively accommodating bearings for supporting the axle are supported by an axlebox suspension and are configured to be displaceable in an upper-lower direction relative to the bogie frame. Problems of such a bogie are that the manufacturing cost is high due to a large number of welded portions, and the weight of the bogie is heavy. Here, PTL 1 proposes a bogie from which side sills are omitted.
Various bogies each having a steering function to improve a traveling stability of the railcar when the railcar travels along a curved line have been proposed. For example, PTL 2 proposes a steering device of a bogie of a railcar, the steering device including a steering beam, a horizontal lever, and a link.